Numerous government agencies, along with utility companies, for example, power producing utilities and state and local highway departments, often use large rotary cutters or rotary mowers to control vegetation along the shoulders of roads or along right-of-ways under power transmission lines, etc. These entities generally operate and/or contract out such vegetation control services which use these large rotary mowers for mowing the right-of-ways as well as the highway and roadway medians and shoulders. These entities have found that in addition to mowing it is conducive to vegetation control to apply certain fluid treatments to the vegetation, including growth regulators, herbicides, pesticides, fungicides and fertilizers or biological agents.
Generally known broadcasting and application methods for such fluid treatment often cause an indiscreet broadcast into the air or randomly dispersed application where some plants are treated and others remain untreated for instance where an operator applying the fluid treatment may not evenly treat the desired vegetation. Atomization of the fluid treatment where the fluid is broken into small, molecular level particle size droplets also increases the problem of random dispersal where wind and environmental factors cause uneven application of the atomized treatment fluid. In these cases, the usefulness of such fluid treatment or herbicide treatments is minimal. Farmers and landowners living near where such chemical treatments and applications occur object to these relatively random applications which can result in tremendous run-off and contamination of their properties and crops. Therefore, it is very important that such chemical treatments be absorbed into the vascular and/or translocation systems of the plant so that it produces the most effective result.
There are a number of known rotary brush cutters and herbicide applicators, including U.S. Pat. No. 4,926,622 to McKee. McKee discloses a number of cutting blades and a system for delivering the herbicide adjacent the cutting blades so that the herbicide is applied to the vegetation as it is being cut by the rotating cutting blades. Also U.S. Pat. No. 5,237,803 to Domingue, Jr. shows a centrifugal applicator which uses a lower pan which throws a fluid treatment against an upper shield which then disperses the fluid treatment above the cutting blades onto the cut vegetation, preferably without getting or collecting the treatment fluid on the blades themselves. Openings in the lower pan are radially spaced from the cutting blades so that the ejected fluid treatment or pesticide does not collect on the cutting blades.
More recently, U.S. Pat. No. 6,125,621 to Burch discloses an apparatus and method for cutting and treating vegetation whereby a herbicide is delivered by a pump in a continuous uninterrupted stream from the supply tank to the cutting blades through the drive shaft of the cutting blade transmission, through a connection bolt and connecting blade hub and onto the bottom surface of a cutting blade. The drawback associated with this reference is two-fold, first the cutting blade is composed of numerous expensive parts which require a tremendous amount of precision in manufacture and assembly and thus create a particularly high cost to both the production and use of such an apparatus and herbicide treating system. Secondly, the manufacture of the drive shaft with a passage for the treatment fluid and the requisite size constraints of the transmission casing in which the drive shaft is located cause the shaft to be modified in such a manner as to compromise its shear strength. Drive shaft failure, transmission tolerances and rebuilding have become a major issue based on this modification. Also, the leakage of any herbicide from this shaft inside the cutting blade transmission will burn out the transmission so that complete failure of the transmission is almost inevitable.